From 9d4209fb82cab74bae76511e3f21ef1c24ec948a Mon Sep 17 00:00:00 2001
From: Jim Laskey <jlaskey@mac.com>
Date: Tue, 7 Nov 2006 19:33:46 +0000
Subject: 1. Add a pass to fold debug label instructions so a debug info client
 can detect empty ranges.

2. Reorg how MachineDebugInfo maintains changes to debug labels.

3. Have dwarf writer use debug label info to simplify scopes and source line
coorespondence.

4. Revert the merging of compile units until I can get the bugs ironed out.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31507 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineDebugInfo.cpp | 102 +++++++++++++++++++++++++++------------
 1 file changed, 71 insertions(+), 31 deletions(-)

(limited to 'lib/CodeGen/MachineDebugInfo.cpp')

diff --git a/lib/CodeGen/MachineDebugInfo.cpp b/lib/CodeGen/MachineDebugInfo.cpp
index 490e48d926..bdbdd144fd 100644
--- a/lib/CodeGen/MachineDebugInfo.cpp
+++ b/lib/CodeGen/MachineDebugInfo.cpp
@@ -10,7 +10,11 @@
 #include "llvm/CodeGen/MachineDebugInfo.h"
 
 #include "llvm/Constants.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineLocation.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Intrinsics.h"
@@ -1448,10 +1452,9 @@ MachineDebugInfo::MachineDebugInfo()
 , Directories()
 , SourceFiles()
 , Lines()
-, LabelID(0)
+, LabelIDList()
 , ScopeMap()
 , RootScope(NULL)
-, DeletedLabelIDs()
 , FrameMoves()
 {}
 MachineDebugInfo::~MachineDebugInfo() {
@@ -1544,35 +1547,6 @@ unsigned MachineDebugInfo::RecordLabel(unsigned Line, unsigned Column,
   return ID;
 }
 
-static bool LabelUIDComparison(const SourceLineInfo &LI, unsigned UID) {
-  return LI.getLabelID() < UID;
-}
- 
-/// InvalidateLabel - Inhibit use of the specified label # from
-/// MachineDebugInfo, for example because the code was deleted.
-void MachineDebugInfo::InvalidateLabel(unsigned LabelID) {
-  // Check source line list first.  SourceLineInfo is sorted by LabelID.
-  std::vector<SourceLineInfo>::iterator I =
-    std::lower_bound(Lines.begin(), Lines.end(), LabelID, LabelUIDComparison);
-  if (I != Lines.end() && I->getLabelID() == LabelID) {
-    Lines.erase(I);
-    return;
-  }
-  
-  // Otherwise add for use by isLabelValid.
-  std::vector<unsigned>::iterator J =
-    std::lower_bound(DeletedLabelIDs.begin(), DeletedLabelIDs.end(), LabelID);
-  DeletedLabelIDs.insert(J, LabelID);
-}
-
-/// isLabelValid - Check to make sure the label is still valid before
-/// attempting to use.
-bool MachineDebugInfo::isLabelValid(unsigned LabelID) {
-  std::vector<unsigned>::iterator I =
-    std::lower_bound(DeletedLabelIDs.begin(), DeletedLabelIDs.end(), LabelID);
-  return I == DeletedLabelIDs.end() || *I != LabelID;
-}
-
 /// RecordSource - Register a source file with debug info. Returns an source
 /// ID.
 unsigned MachineDebugInfo::RecordSource(const std::string &Directory,
@@ -1642,4 +1616,70 @@ DebugScope *MachineDebugInfo::getOrCreateScope(DebugInfoDesc *ScopeDesc) {
   return Slot;
 }
 
+//===----------------------------------------------------------------------===//
+/// DebugLabelFolding pass - This pass prunes out redundant debug labels.  This
+/// allows a debug emitter to determine if the range of two labels is empty,
+/// by seeing if the labels map to the same reduced label.
+
+namespace llvm {
+
+struct DebugLabelFolder : public MachineFunctionPass {
+  virtual bool runOnMachineFunction(MachineFunction &MF);
+  virtual const char *getPassName() const { return "Debug Label Folder"; }
+};
+
+bool DebugLabelFolder::runOnMachineFunction(MachineFunction &MF) {
+  // Get machine debug info.
+  MachineDebugInfo *MDI = getAnalysisToUpdate<MachineDebugInfo>();
+  if (!MDI) return false;
+  // Get target instruction info.
+  const TargetInstrInfo *TII = MF.getTarget().getInstrInfo();
+  if (!TII) return false;
+  // Get target version of the debug label opcode.
+  unsigned DWARF_LABELOpc = TII->getDWARF_LABELOpcode();
+  if (!DWARF_LABELOpc) return false;
+  
+  // Track if change is made.
+  bool MadeChange = false;
+  // No prior label to begin.
+  unsigned PriorLabel = 0;
+  
+  // Iterate through basic blocks.
+  for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
+       BB != E; ++BB) {
+    // Iterate through instructions.
+    for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
+      // Is it a debug label.
+      if ((unsigned)I->getOpcode() == DWARF_LABELOpc) {
+        // The label ID # is always operand #0, an immediate.
+        unsigned NextLabel = I->getOperand(0).getImm();
+        
+        // If there was an immediate prior label.
+        if (PriorLabel) {
+          // Remap the current label to prior label.
+          MDI->RemapLabel(NextLabel, PriorLabel);
+          // Delete the current label.
+          I = BB->erase(I);
+          // Indicate a change has been made.
+          MadeChange = true;
+          continue;
+        } else {
+          // Start a new round.
+          PriorLabel = NextLabel;
+        }
+       } else {
+        // No consecutive labels.
+        PriorLabel = 0;
+      }
+      
+      ++I;
+    }
+  }
+  
+  return MadeChange;
+}
+
+FunctionPass *createDebugLabelFoldingPass() { return new DebugLabelFolder(); }
+
+}
 
-- 
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